The present invention relates to a rolling steel door, and more particularly to a light structure of rolling steel door, which needs less storage space when rolled up.
FIGS. 6 and 7 show a rolling steel door according to the prior art. This structure of rolling steel door comprises a plurality of solid metal transverse rods 2, a plurality of sleeves respectively sleeved onto the metal transverse rods 2, and a plurality of links 3 respectively coupled to the metal transverse rods 2 to hold the metal transverse rods in parallel. The links 3 are respectively formed of two symmetrical half shells 31. Each link 3 has two coupling holes 311 disposed at two distal ends, and respectively coupled to a respective metal transverse rod 2. Because each link 3 is formed of two symmetrical half shells 31, the coupling holes 311 have a certain depth, i.e., each link 3 has a broad contact area adapted to support the metal transverse rods 2. Further, in order to diminish the weight, the metal transverse rods 2 have a hollow structure. However, this structure of rolling steel door still has drawbacks as outlined hereinafter.
1. Because the links 3 are respectively formed of two symmetrical half shells 31, the links 3 are less stable when taking up or letting off the rolling steel door, resulting in high noise.
2. Because the links 3 are respectively formed of two symmetrical half shells 31, the coupling holes of the respective pair of half shells 31 may be not perfectly aligned, causing the links 3 unable to keep the metal transverse rods 2 in parallel perfectly.
3. Because the links 3 are respectively formed of two symmetrical half shells 31, it is complicated to install the links 3.
The present invention has been accomplished to provide links for rolling steel door, which eliminates the aforesaid drawbacks. It is one object of the present invention to provide a link for rolling steel door, which has high strength. It is another object of the present invention to provide a link for rolling steel door, which produces less noise during the operation of the rolling steel door. It is still another object of the present invention to provide a link for rolling steel door, which facilitates the assembly of the rolling steel door. It is still another object of the present invention to provide a link for rolling steel door, which causes a sense of beauty. According to one embodiment of the present invention, the link is formed of a body and a cover plate covered on the body. The body comprises two short coupling tubes, and a peripheral flange at one side. The cover plate comprises two coupling holes respectively coupled to the coupling tubes of the body, and a peripheral flange abutted against the peripheral flange of the body. The end of each short coupling tube is expanded by a punch press to fixedly secure the cover plate to the body after its insertion through the respective coupling hole on the cover plate. According to an alternate form of the present invention, the body has two coupling holes, which receive the short coupling tubes respectively. After inserted through the coupling holes of the body, the short coupling tubes are respectively expanded by a punch press, and therefore the short coupling tubes and the body are fixedly fastened together.